Method of forming tire component member

ABSTRACT

There is provided a tire structural member forming method capable of forming a structural member of a tire for a vehicle at a low cost, using a simple mechanism satisfactory in space efficiency and capable of setting a band-shaped member of a predetermined length on a forming drum in a high setting accuracy. The tire structural member forming method comprises the steps of applying a band-shaped member ( 3 ) of a predetermined length and a predetermined width to a transfer drum ( 12 ), moving the transfer drum ( 12 ) holding the band-shaped member ( 3 ) close to a forming drum ( 11 ) of a diameter smaller than that of the transfer drum ( 12 ) so that the leading end of the band-shaped member ( 3 ) is held between the transfer drum ( 12 ) and the forming drum ( 11 ), turning the transfer drum ( 12 ) and the forming drum ( 11 ) in opposite directions, respectively, at the same surface speed to transfer the band-shaped member ( 3 ) from the transfer drum ( 12 ) to the forming drum ( 11 ), and bonding together the leading and the trailing end of the band-shaped member ( 3 ) wound around the forming drum ( 11 ) to form a tire structural member on the forming drum ( 11 ).

TECHNICAL FIELD

The present invention relates to a tire structural member forming methodof forming a tire structural member, such as plies or an inner liner, ona forming drum.

BACKGROUND ART

One of three types of tire structural member forming systems shown inFIGS. 5 to 7 is used for forming an annular tire structural member of anautomotive tire by winding a band-shaped member of a predeterminedlength around a forming drum and bonding together the leading and thetrailing end of the band-shaped member.

The first tire structural member forming system shown in FIG. 5 carriesa band-shaped member 01 by a conveyor belt 03 to feed the band-shapedmember 01 to a forming drum 02 disposed close to the delivery end of theconveyor belt 03. The belt-shaped member 01 is wound around the formingdrum 02 from its leading edge.

The second tire structural member forming system shown in FIG. 6 placesa band-shaped member 01 on a flat plate 05 and moves the flat plate 05supporting the band-shaped member 01 horizontally to bring theband-shaped member 01 close to a rotating forming drum 02. Then, theband-shaped member 01 is wound from its leading edge around the rotatingforming drum 02.

The third tire structural member forming system shown in FIG. 7 carriesa band-shaped member 01 of a predetermined length by robot hands 07 and08. The robot hands 07 and 08 hold the band-shaped member 01 at theleading end and at the trailing end, respectively, by gripping or bysuction and carry the band-shaped member 01 to a forming drum 02. Therobot hand 07 releases the leading end of the band-shaped member 01 at aposition corresponding to the circumference of the forming drum 02.Then, the forming drum 02 is rotated and the other robot hand 08 ismoved as the band-shaped member 01 is wound around the forming drum 02.

When the band-shaped member 01 is carried by the first tire structuralmember forming system using the conveyor belt 03 as shown in FIG. 5, theconveyor belt 03 meanders. Therefore, it is possible that theband-shaped member 01 cannot be correctly located (centered) relative tothe forming drum 02. When the band-shaped member 01 of a predeterminedlength is built by successively superposing and bonding together stripsobtained by cutting a long band in the predetermined length on theconveyor belt 03 with their edges trued up, the strips cannot beaccurately bonded together because the feed rate of the conveyor belt 03varies.

When the band-shaped member 01 is carried by the second tire structuralmember forming system using the flat plate 05 as shown in FIG. 6, theband-shaped member 01 can be set correctly. However, the long flat plate05 needs to be moved horizontally by a distance nearly equal to itslength. Therefore, a large space must be secured for the flat plate 05to move horizontally and hence the second tire structural member formingsystem is unsatisfactory in space efficiency.

Although the robot hands 07 and 08 used by the third tire structuralmember forming system as shown in FIG. 7 are capable of accuratelysetting the band-shaped member 01 relative to the forming drum 02, thethird tire structural member forming system is complicated.

The present invention has been made in view of the foregoing problemsand it is therefore an object of the present invention to provide a tirestructural member forming method capable of accurately setting aband-shaped member of a predetermined length on a forming drum, ofefficiently using space and of forming the tire structural member at alow cost by a simple mechanism.

DISCLOSURE OF THE INVENTION

To achieve the object, according to a first aspect of the presentinvention, a tire structural member forming method comprises the stepsof: applying a band-shaped member of a predetermined length and apredetermined width to a transfer drum; moving the transfer drumcarrying the band-shaped member relative and close to a forming drum ofa diameter smaller than that of the transfer drum so that the leadingend of the band-shaped member is held between the transfer drum and theforming drum; turning the transfer drum and the forming drum in oppositedirections, respectively, at the same surface speed to transfer theband-shaped member from the transfer drum to the forming drum; andbonding together the leading and the trailing end of the band-shapedmember wound around the forming drum to form a tire structural member onthe forming drum.

This tire structural member forming method uses the simple transfer druminstead of the horizontally movable flat plate, the band-shaped memberof the predetermined length can accurately be transferred from thetransfer drum to the forming drum and can accurately be set on theforming drum, and the tire structural member forming method can becarried out by a low-cost system excellent in space efficiency.

According to a second aspect of the present invention, a tire structuralmember forming method comprises the steps of: cutting a long band intosuccessive strips of a predetermined width and a predetermined length;forming a band-shaped member of a predetermined length substantiallyequal to the circumference of a forming drum by applying a predeterminednumber of the strips to a transfer drum of a diameter greater than thatof the forming drum in a circumferential arrangement with side edges ofadjacent strips overlapping each other; bringing the transfer drumholding the band-shaped member relative and close to the forming drum tohold the leading end of the band-shaped member between the transfer drumand the forming drum; transferring the band-shaped member from thetransfer drum to the forming drum by turning the transfer drum and theforming drum in the opposite directions, respectively, at the samesurface speed; and forming a tire structural member on the forming drumby bonding together the leading and the trailing end of the band-shapedmember transferred to the forming drum.

Since this tire structural member forming method forms the band-shapedmember on the transfer drum by applying the predetermined number of thestrips to the transfer drum in a circumferential arrangement with sideedges of the adjacent strips overlapping each other, accuracy of bondingthe strips can be improved by controlling the angle of rotation of thetransfer drum.

Since the band-shaped member can be transferred from the transfer drumto the forming drum and can be set on the forming drum in a highaccuracy, a high-quality tire structural member can be formed. This tirestructural member forming method can be carried out by a low-cost systemexcellent in space efficiency.

In each of those tire structural member forming methods, the stripsapplied to the transfer drum may be held on the transfer drum bysuction.

Since the strips are held by suction on the transfer drum, the stripsare not dislocated, are able to retain their shapes, and a high bondingaccuracy can be insured. The strips can readily be released from thetransfer drum by removing the suction to facilitate transferring thestrips from the transfer drum to the forming drum, and hence settingaccuracy can be improved.

The transfer drum employed in carrying out the foregoing tire structuralmember forming methods may be finished by a surface treatment such thatthe band-shaped member applied to the transfer drum can be easilyseparated from the transfer drum.

Since the transfer drum is finished by the surface treatment to enablethe band-shaped member to be separated easily from the transfer drum,setting accuracy can be improved.

In the foregoing tire structural member forming method, the transferdrum may be moved toward and away from the forming drum by swinging ortranslating the transfer drum.

The transfer drum can simply be swung or translated and hence the systemis excellent in space efficiency and can be manufactured at a low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevation of a forming drum and a transferdrum;

FIG. 2 is a schematic sectional view of the transfer drum, showinginternal mechanisms of the transfer drum;

FIGS. 3-1, 3-2 and 3-3 are views of assistance in explaining successivesteps of work for forming plies on the forming drum;

FIGS. 4-1 and 4-2 are views of assistance in explaining steps followingthe step shown in FIG. 3-3;

FIG. 5 is a schematic view of a conventional tire structural memberforming system for forming a tire structural member on a forming drum;

FIG. 6 is a schematic view of another conventional tire structuralmember forming system for forming a tire structural member on a formingdrum; and

FIG. 7 is a schematic view of a third conventional tire structuralmember forming system for forming a tire structural member on a formingdrum.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the present invention will be described withreference to FIGS. 1 to 4.

Referring to FIGS. 1 and 2, a forming drum 11 of a diameter D isinstalled with its center axis extended in a horizontal direction. Atransfer drum 12 of a diameter greater than the diameter D is supportedfor a swinging motion with its center axis extended parallel with thatof the forming drum 11.

Support shafts 13 supporting the transfer drum 12 at its opposite endsare supported for rotation on upper end parts of swing arms 14,respectively. Lower base end parts of the swing arms 14 are supported onpivotal shafts 15 which in turn are supported coaxially on fixed supportmembers 30.

The swing arms 14 supporting the transfer drum 12 on its upper end partsturn forward and backward (to the right and the left as viewed inFIG. 1) to move the transfer drum 12 toward and away from the formingdrum 11.

A sprocket 16 is mounted on one of the support shafts 13 connected tothe transfer drum 12, a sprocket 18 is mounted on the pivotal shaft 15supporting the lower base end part of one of the swing arms 14, and achain 19 is extended between the sprocket 16 and 18. The pivotal shaft15 provided with the sprocket 18 is coupled coaxially with the driveshaft 17 a of a motor 17. The motor 17 drives the transfer drum 12through the chain 19 for rotation on the support shaft 13.

The transfer drum 12 has a cylindrical drum body 12 a provided with manythrough holes 12 b. A vacuum mechanism 20 is placed in the cylindricaldrum body 12 a.

A screw 21 is extended between the support shafts 13 and is supportedfor rotation. External threads of opposite hands are formed in right andleft parts, respectively, of the screw 21. Nuts 24 attached to centralparts of partition disk 22 partitioning the interior of the cylindricaldrum body 12 a are engaged with the external threads of the screw 21.

The partition disks 22 are symmetric with respect to a center plane.Cylindrical members 23 of substantially the same diameter extend fromthe partition disks 22 toward each other such that an inner end part ofone of the cylindrical members 23 is fitted in an inner end part of theother cylindrical member 23.

Thus, the right and the left partition disk 22 and the cylindricalmembers 23 define an annular vacuum chamber 25 (dotted area in FIG. 2)in the cylindrical drum body 12 a. The through holes 12 b open into thevacuum chamber 25.

A timing belt 29 is extended between a pulley 27 mounted on the driveshaft of a motor disposed in the cylindrical drum body 12 a, and apulley 28 mounted on the screw 21.

When the motor 26 drives the screw 21 for rotation through the timingbelt 29, the partition disks 22 fastened to the nuts 24 engaged with theexternal threads of the screw 21 are moved axially in oppositedirections, respectively, to expand or contract the vacuum chamber 25.

When a pump, not shown, operates to evacuate the vacuum chamber 25 to avacuum, air is sucked through the through holes 12 b into the vacuumchamber 25 to attract strips 2 to the outer surface of the cylindricaldrum body 12 a by suction.

The position of the partition disks 22 are adjusted such that the axiallength of the vacuum chamber 25 corresponds to the length of the strips2 to attract the strips 2 efficiently to the circumference of thecylindrical drum body 12 a.

The strips 2 attracted to the circumference of the cylindrical drum body12 a can be easily separated from the circumference of the cylindricaldrum body 12 a by supplying low-pressure air into the vacuum chamber 25to blow air outward through the through holes 12 b.

The circumference of the cylindrical drum body 12 a is finished by asurface treatment such that the strips can easily be separated from thecircumference of the cylindrical drum body 12 a.

The transfer drum 12 is thus constructed. Steps of work for forming aply 4, i.e., a tire structural member, on the forming drum 11 will bedescribed with reference to FIGS. 3 and 4.

Referring to FIG. 3-1, the transfer drum 12 is set apart from theforming drum 11. An inner liner 1 is wound around the forming drum 11,while the strips 2 of a predetermined length are arranged successivelyon the circumference of the transfer drum 12 in a circumferentialdirection with the side edges of the adjacent strips 2 overlapping eachother. The strips 2 thus arranged are attracted to the circumference ofthe transfer drum 12 by suction exerted thereon by the vacuum mechanism20.

The strips 2 are formed by cutting a long, band of a predetermined widthof πD/n (n is an integer) formed by coating a plurality of cords withrubber by an extrusion process in a predetermined length (sectionwidth).

The strips 2 are fed successively from a predetermined position onto theintermittently turned transfer drum 12 so that the side edges of theadjacent strips 2 overlap each other.

The distance between the partition disks 22 of the vacuum mechanism 20is adjusted beforehand to the section width of the strips 2 to form thevacuum chamber 25 properly.

Since the vacuum mechanism 20 attracts the strips 2 to the transfer drum12 by suction, the strips 2 are not dislocated, are able to retain theirshapes, and a high bonding accuracy can be insured.

Thus, the n strips 2 of πD/n in width are applied successively to thetransfer drum 12 to form the band-shaped member 3 of a predeterminedlength substantially equal to the circumference πD of the forming drum11 and a width equal to the section width is formed on the transfer drum12 as shown in FIG. 3-2.

Then, the swing arms 14 are turned to move the transfer drum 12 towardthe forming drum 11 so that the leading end of the band-shaped member 3is held between the drums 11 and 12 as shown in FIG. 3-3.

Then, the forming drums 11 and the transfer drum 12 are turned inopposite directions, respectively, to transfer the band-shaped member 3from the transfer drum 12 to the forming drum 11 as shown in FIG. 4-1.

Suction is removed from the strips 2 or air is blown outward at atransfer position to facilitate the separation of the strips 2 from thetransfer drum 12. Since the adhesive inner liner 1 is wound around theforming drum 11, the band-shaped member 3 is transferred smoothly.

The band-shaped member 3 can be transferred from the transfer drum 12 tothe forming drum 11 and can be set on the forming drum 11 in a very highsetting accuracy.

The band-shaped member 3 is wound around the inner liner 1 wound aroundthe forming drum 11 so as to cover the inner liner 1 entirely as shownin FIG. 4-2 because the length of the band-shaped member 3 issubstantially equal to the circumference πD of the forming drum 11. Theleading and the trailing end of the band-shaped member 3 are bondedtogether to form the ply 4.

Since the band-shaped member can be transferred from the transfer drum12 to the forming drum 11 and can be set on the forming drum 11 in ahigh setting accuracy, the ply 4 has a high quality. The swingabletransfer drum 12 having a cylindrical shape is excellent in spaceefficiency, simple in construction and capable of reducing cost.

The transfer drum may be translated, and the forming drum may be movedtoward and away from the transfer drum.

Other tire structural members, such as belts, can be superposed on theinner liner 1 and forming work can be carried out while the transferdrum 12 is separated from the forming drum 11 after the ply 4 has beenformed on the forming drum, and then strips 2 are applied again to thetransfer drum 12, and hence working efficiency is excellent.

The transfer drum 12 is provided with the vacuum mechanism 20 to holdthe ply 4 on the transfer drum 12 by suction in the foregoingembodiment. If the ply includes embedded steel cords, electromagnets maybe arranged on the inner circumference of the transfer drum and the plymay be attracted to the transfer drum by magnetism

The ply can be easily separated from the transfer drum by stopping thesupply of current to the electromagnets.

The transfer drum does not need to be a cylindrical drum; a transferdrum having the shape of a polygonal prism may be used.

The inner liner may be transferred from the transfer drum 12 to theforming drum 11.

The forming drum may be provided with a vacuum mechanism orelectromagnets, and the ply and such transferred to the forming drum maybe held on the forming drum by suction or magnetism.

1. A tire structural member forming method comprising the steps of:providing a forming drum of a diameter on which a tire structural memberin the form of a band-shaped member is to be formed, and a transfer drumof a diameter greater than the diameter of the forming drum; determininga width of said band-shaped member by dividing the circumference of saidforming drum by a predetermined integer; cutting a long band having thethus determined width into successive strips of a predetermined length;applying a predetermined number equal to said integer of the stripssuccessively in a circumferentially adjoining arrangement onto thetransfer drum with side edges of adjacent strips overlapping each other,while the transfer drum is held stationarily at a position and turnedintermittently at that position, to thus obtain the band-shaped memberhaving a predetermined length which is substantially equal to thecircumfrence of the forming drum; moving the transfer drum holding theband-shaped member away from said position to another position close tothe forming drum to hold a leading end of the band-shaped member betweenthe transfer drum and the forming drum; transferring the band-shapedmember from the transfer drum to the forming drum by turning thetransfer drum and the forming drum in opposite directions, respectively,at the same surface speed, whereby the leading end and a trailing end ofthe band-shaped member are brought into abutting contact with eachother; and forming a tire structural member on the forming drum bybonding together the leading end and the trailing end of the band-shapedmember transferred to the forming drum.
 2. The tire structural memberforming method according to claim 1, wherein the band-shaped member isapplied to and held on the transfer drum by suction from within thetransfer drum.
 3. The tire structural member forming method according toclaim 1, wherein the transfer drum is finished by a surface treatmentsuch that the band-shaped member applied to the transfer drum can beeasily separated from the transfer drum.
 4. The tire structural memberforming method according to claim 1, wherein the transfer drum is movedtoward and away from the forming drum by swinging or translation.
 5. Thetire structural member forming method according to claim 1, furthercomprising: urging the band-shaped member that is being transferred fromthe transfer drum to the forming drum, away from the transfer drum, tothereby press the band-shaped member against the forming drum.
 6. Thetire structural member forming method according to claim 1, wherein thestrips are applied to and held on the transfer drum by suction fromwithin the transfer drum, and the band-shaped member is urged away fromthe transfer drum by switching from the suction to outward air blowingfrom within the transfer drum.